In a major victory for environmentalists, the California Coastal Commission rejected a proposal to build a six-lane toll road through the San Onofre State Beach park, a popular nature preserve known for its wildlife and world-class surf breaks.

After a marathon hearing before a crowd of thousands, commissioners in Del Mar, Calif., voted 8 to 2 against the proposed Foothill South toll road, a six-lane, 16-mile extension to Route 241.

The vote, which was greeted by an enormous cheer, followed 12 hours of public testimony from the crowd, of whom 2,500 made formal requests to speak, the largest number for a hearing in the commission's more than 30 years of operation.

Some arrived by bus, brought by surf-industry companies opposed to the project. Others came as members of construction unions that support it. Some in the crowd carried surfboards as a symbol of protest. Others dressed as if attending a long-awaited football game.

The noisy crowd sat in rows of chairs and banks of bleachers at the rear of Wyland Hall at Del Mar Fairgrounds to participate in a long-awaited showdown over a road proposal that has generated intense public interest across the state.

Supporters of the proposed road, who include California Gov. Arnold Schwarzenegger and the Transportation Corridor Agencies, two state-established authorities that build, finance, and operate Orange County's toll roads, argue that the extension is necessary to relieve congestion, particularly on southern Interstate 5. They cite reports that say that, by 2025, rush-hour travel times on the 16-mile stretch of the I-5 from the San Diego County line to the Oso Parkway would be one hour instead of 25 minutes.

Many parts of California are becoming known for gridlock and crumbling roads, rather than for the magic of our coastline. That is unacceptable to me. Our freeways were built for a population of 18 million, and today these critical arteries are clogged with cars and trucks serving a population of 37 million. Every mile of stopped traffic poisons our air with tons of carbon and pollution, undermining all the great work we've done to clean our air and reduce greenhouse gas emissions.

Environmentalists say that the road would take over 60 percent of the park's acreage, close a popular campground, and pollute the park's watershed with highway runoff. Moreover, they say that the road would block natural sediment flow, disrupting the legendary breaks at Trestles, a collection of spots known to surfers worldwide.

The toll road is also opposed by native American groups, as the road would come close to an ancient burial site.